1. Field of the Invention
The present invention relates to systems and methods for examining biological material. In particular, the invention relates to the acquisition of images by exposing biological probe arrays comprising probe features to an excitation light and detecting the responsive emitted light from fluorescent labels associated with target molecule hybridized to the probes of one or more probe features. For example, the system comprises a CCD based optical architecture using a microscope lens to collect light emitted from the target and employs high powered LED's as light sources. In the present example, a first LED may be employed for auto-focus functions using a wavelength that is outside the excitation the fluorescent labels and a second LED employed for providing excitation light within the range of excitation range.
2. Related Art
Synthesized nucleic acid probe arrays, such as Affymetrix GeneChip® probe arrays, and spotted probe arrays, have been used to generate unprecedented amounts of information about biological systems. For example, the GeneChip® Human Genome U133 Plus 2.0 Array for expression applications available from Affymetrix, Inc. of Santa Clara, Calif., is comprised of one microarray containing 1,300,000 oligonucleotide features covering more than 47,000 transcripts and variants that include 38,500 well characterized human genes. Similarly, the GeneChip® Mapping 500K Array Set for genotyping applications available from Affymetrix, Inc. of Santa Clara, Calif., is comprised of two arrays, each capable of genotyping on average 250,000 SNPs. Analysis of expression or genotyping data from such microarrays may lead to the development of new drugs and new diagnostic tools.